JP7621389B2 - Terminal device and wireless communication method - Google Patents

Description

The present invention relates to a terminal device and a wireless communication method.

3GPP (Third Generation Partnership Project), an international standardization organization, is studying NR (New Radio), a new wireless access technology for the fifth generation (5G: Fifth Generation) cellular communication system. NR is a technology that is being studied to realize a wider variety of services than LTE (Long Term Evolution)-Advanced, the fourth generation cellular communication system. For example, NR defines different usage scenarios as requirements for realization, such as eMBB (enhanced Mobile Broadband) that realizes high-speed, large-capacity communication, URLLC (Ultra-Reliable and Low Latency Communication) that realizes ultra-reliable, low-latency communication, and mMTC (massive Machine Type Communication) that realizes multiple simultaneous connections of IoT (Internet of Things) devices.

In NR, antenna technology is adopted to improve the throughput of wireless communication. For example, wireless communication using millimeter waves is possible in NR. When wireless communication is performed using a relatively high frequency band such as millimeter waves, propagation loss increases. To prevent such problems, a technology (beamforming) is known that forms beams with a relatively narrow beam width. In addition, NR adopts MIMO (Multiple Input Multiple Output), a technology that has multiple antennas on both the transmitting and receiving sides and divides transmission data into multiple antennas and transmits them in parallel (see Non-Patent Document 1).

Furthermore, NR employs carrier aggregation (CA), which enables the expansion of bandwidth by aggregating (bundling) multiple frequency bands, such as 20 MHz, called component carriers (CCs). Regarding this carrier aggregation, in order to set the MIMO layers of each component carrier when carrier aggregation is performed, the base station device obtains information on the number of MIMO layers for each of multiple component carriers from the terminal device as the terminal device's own terminal capability information ("UECapabilityInformation") (see Non-Patent Document 2).

3GPP standard "TS 38.331" 3GPP standard document “TS 38.306-1”

As described above, in NR, at the start of a connection, the base station device acquires information regarding the number of MIMO layers for each of the multiple component carriers of the carrier aggregation from the terminal device. In other words, the terminal device needs to transmit a lot of terminal capability information about itself to the base station device. Therefore, there is a risk that the utilization efficiency of wireless communication resources between the terminal device and the base station device will decrease.

The present invention has been made in consideration of these circumstances, and aims to provide a wireless communication technology for improving the utilization efficiency of wireless communication resources between a terminal device and a base station device.

A terminal device according to one aspect of the present invention is a terminal device in a mobile communication system compatible with carrier aggregation, and includes an acquisition unit that acquires the number of layers for each of a plurality of component carriers, and a transmission unit that transmits to a base station device a first number of layers for a first band including a first number of component carriers and a second number of layers for a second band including a second number of component carriers less than the first number, and the transmission unit omits transmission to the base station device of a third number of layers for a third band including a third number of component carriers less than the first number and more than the second number when each of the first number of layers and the second number of layers satisfy a predetermined condition.

A wireless communication method according to one aspect of the present invention is a wireless communication method used by a terminal device in a mobile communication system compatible with carrier aggregation, and includes the steps of acquiring the number of layers for each of a plurality of component carriers, and transmitting to a base station device a first number of layers for a first band including a first number of component carriers and a second number of layers for a second band including a second number of component carriers less than the first number, wherein the transmitting step omits transmission to the base station device of a third number of layers for a third band including a third number of component carriers less than the first number and more than the second number when each of the first number of layers and the second number of layers satisfy a predetermined condition.

According to the present invention, it is possible to provide a wireless communication technology for improving the utilization efficiency of wireless communication resources between a terminal device and a base station device.

FIG. 1 is a diagram showing an example of a schematic configuration of a mobile communication system according to an embodiment. FIG. 2 is a diagram illustrating an example of a hardware configuration of a terminal device and a base station device in an embodiment. FIG. 3 is a diagram illustrating an example of a functional block configuration of a terminal device according to an embodiment. FIG. 4 is a diagram illustrating an example of a functional block configuration of a base station device according to an embodiment. FIG. 5 is a flowchart showing an example of a MIMO layer setting process in carrier aggregation in the first embodiment. FIG. 6 is a conceptual diagram showing an example of a transmission process of terminal capability information ("UECapabilityInformation") in the first embodiment. FIG. 7 is a flowchart showing an example of a MIMO layer setting process in carrier aggregation in the second embodiment. FIG. 8 is a flowchart showing an example of a MIMO layer setting process in carrier aggregation in the third embodiment. FIG. 9 is a conceptual diagram showing an example of a process for transmitting terminal capability information in the third embodiment. FIG. 10 is a conceptual diagram illustrating another example of the terminal capability information transmission process in an embodiment.

An embodiment of the present invention is described below. In the following description of the drawings, identical or similar parts are represented by identical or similar symbols. However, the drawings are schematic. Therefore, specific dimensions, etc. should be determined in light of the following description. Furthermore, the drawings include parts with different dimensional relationships and ratios. Furthermore, the technical scope of the present invention should not be interpreted as being limited to the embodiment.

With reference to Figure 1, a schematic configuration of a mobile communication system compatible with Carrier Aggregation (CA) in one embodiment will be described. Carrier aggregation CA processing refers to processing that enables bandwidth expansion by aggregating (bundling) multiple frequency bands, for example 20 MHz, called component carriers (CCs). Figure 1 is a configuration diagram showing an example of the schematic configuration of a mobile communication system 100 in one embodiment.

As shown in FIG. 1, the mobile communication system 100 includes terminal devices 10-1 to 10-m, base station devices 50-1 to 50-n, and a core network device 90. Note that FIG. 1 illustrates terminal devices 10-1 to 10-m as m terminal devices (m is an integer of 2 or more). In the following description, when describing these m terminal devices without distinction, some of the reference numerals are omitted and they are simply referred to as "terminal device 10". Also, FIG. 1 illustrates base station devices 50-1 to 50-n as n base station devices (n is an integer of 2 or more). In the following description, when describing these n base station devices without distinction, some of the reference numerals are omitted and they are simply referred to as "base station device 50".

Here, an overview of the mobile communication system 100 in the first embodiment of the present invention will be described. As described above, in NR, when carrier aggregation (CA) is performed, the terminal device needs to transmit a lot of terminal capability information of the terminal device itself to the base station device. Therefore, there is a risk that the utilization efficiency of wireless communication resources between the terminal device and the base station device will decrease.

One method for improving the efficiency of utilization of wireless communication resources between a terminal device and a base station device is, for example, to omit transmission of some of the terminal capability information related to fallback CA (for example, when a maximum of M CCs can be used in CA, this refers to CA that uses N CCs, where N is an integer smaller than M; M is, for example, an integer smaller than 5).

Figure 10 is a conceptual diagram showing an example of a terminal capability information transmission process in one embodiment. In particular, Figure 10 is a diagram showing an example of transmitting terminal capability information from a terminal device to a base station device when the terminal device implements eight antenna paths (8RF paths) in Intra band 4CC CA, which can use up to four CCs in Intra band CA. For example, for a fallback CA (e.g., Intra band 3CC CA and Intra band 2CC CA in Figure 10), if the terminal device supports the same functions as the highest Intra band 4CC CA, there is a method of making it possible to omit the transmission of terminal capability information for the fallback CA. The highest Intra band 4CC CA includes CC #0 (2×2), CC #1 (2×2), CC #2 (2×2) and CC #3 (2×2) which all have a MIMO layer number of "2" in the frequency band, so the transmission of information regarding the number of MIMO layers of the fallback CA having the same combination of CCs (2×2) is omitted. That is, the terminal device can omit the transmission of information regarding CC #0 (2×2), CC #1 (2×2) and CC #2 (2×2) in the fallback CA (Intra band 3CC CA). Also, the terminal device can omit the transmission of information regarding CC #0 (2×2) and CC #1 (2×2) in the fallback CA (Intra band 2CC CA).

However, as shown in Fig. 10, for Intra band 3CC CA, for example, information regarding the number of MIMO layers of CC #0 (4x4), CC #1 (2x2), and CC #2 (2x2) needs to be transmitted. That is, in the example of Fig. 10, Intra band 3CC CA includes CC #0 (4x4) with a number of MIMO layers "4" different from the number of MIMO layers "2" common to each CC in the highest Intra band 4CC CA. Therefore, since it cannot be said that the same functions as the highest Intra band 4CC CA are supported in the Intra band 3CC CA, the terminal device must transmit information regarding the number of MIMO layers of CC #0 (4x4), CC #1 (2x2) and CC #2 (2x2) in the Intra band 3CC CA to the base station device. Similarly, since the Intra band 2CC CA includes CC #0 (4x4) and CC #1 (4x4), it cannot be said that the same functions as the highest Intra band 4CC CA are supported, so the terminal device must transmit information regarding the number of MIMO layers of CC #0 (4x4) and CC #1 (4x4) in the Intra band 2CC CA to the base station device.

In the above method, it is only possible to omit transmission of some of the information related to the number of MIMO layers in fallback CA. In other words, it is not sufficient as a method for improving the utilization efficiency of wireless communication resources between a terminal device and a base station device.

Therefore, in a mobile communication system according to an embodiment of the present invention, a terminal device transmits to a base station device the first number of layers of the frequency band (first band) of the highest Intra band 4CC CA including four (first number) component carriers (CCs) and the second number of layers of the frequency band (second band) of the lowest 1CC including one (second number) CC that is less than four (first number). When the first number of layers and the second number of layers satisfy a predetermined condition, the terminal device omits transmission to the base station device of the third number of layers of the frequency band (third band) of the fallback CA including two or three (third number) CCs that are less than four (first number) and more than one (second number).

Therefore, the terminal device can largely reduce the amount of terminal capability information to be transmitted to the base station device. This improves the efficiency of use of wireless communication resources between the terminal device and the base station device.

Returning to FIG. 1, the mobile communication system 100 is, for example, a mobile communication system that targets NR. Note that the present invention is applicable to any mobile communication system that includes at least a terminal device and a base station device, and is not limited to those that target NR. For example, the present invention is also applicable to LTE and LTE-Advanced. It is also applicable to a mobile communication system that uses NR as part of the mobile communication system. Hereinafter, LTE and LTE-Advanced are also referred to as E-UTRA (Evolved Universal Terrestrial Radio Access), but the meaning is the same. An area (coverage area) formed by a base station device is called a cell, and E-UTRA and NR are cellular communication systems constructed by multiple cells. The mobile communication system according to this embodiment may apply either TDD (Time Division Duplex) or FDD (Frequency Division Duplex), and different methods may be applied to each cell.

Each of the terminal devices 10-1 to 10-m is wirelessly connected to one of the base station devices 50-1 to 50-n. Also, each of the terminal devices 10-1 to 10-m may be wirelessly connected to two or more of the base station devices 50-1 to 50-n at the same time. Each of the base station devices 50-1 to 50-n may use E-UTRA or NR. For example, the base station device 50-1 may use NR and the base station device 50-n may use E-UTRA, or vice versa. A base station device in E-UTRA is called eNB (evolved NodeB), and a base station device in NR is called gNB (g-NodeB).

Hereinafter, when the term "base station device" is used, it includes both eNB and gNB. In addition, terminal devices in E-UTRA and NR are called UE (User Equipment). In NR, the base station device gNB may connect to terminal devices using a part of the frequency band it uses (BWP: Carrier bandwidth part). Hereinafter, when the term "cell" is used, it includes BWP.

The communication terminal 10 may be, for example, a portable information and communication device such as an IoT device, a smartphone, a mobile phone, a personal digital assistant (PDA), a tablet terminal, a portable game machine, a portable music player, or a wearable terminal. The terminal device 10 may be connected to the base station device 50 on a cell-by-cell basis, and may be connected using multiple cells, for example, by carrier aggregation. When the terminal device 10 is connected via multiple base station devices, that is, in the case of dual connectivity, the base station device that is initially connected is called a master node (MN), and the base station device that is additionally connected is called a secondary node (SN). The base station devices are connected to each other by a base station interface. The base station device 50 and the core network device 90 are connected to each other by a core interface. The base station interface is used to exchange control signals necessary for handover and cooperative operations between the base station devices.

The core network device 90, for example, has base station device 50 under its control, and mainly handles load control between base station devices, calling (paging) terminal device 10, location registration, and other mobility control. In NR, the core network device 90 is specified as a group of control plane (C-plane) functions, including an Access and Mobility Management Function (AMF) that manages mobility and a Session Management Function (SMF) that manages sessions. In E-UTRA, an MME (Mobility Management Entity) that corresponds to the AMF is specified.

Note that, although FIG. 1 shows an example in which the core network device 90 is composed of one device, this is not limited to this. For example, the core network device may be composed of multiple devices, including a server, a gateway, etc.

The terminal device 10 and the base station device 50 transmit and receive RRC messages in the Radio Resource Control (RRC) layer and proceed with session processing (also called a connection sequence). As the session processing proceeds, the terminal device 10 changes from an idle state (RRC Idle) to a connected state (RRC Connected) to the base station device 50. The idle state corresponds to the standby state of the terminal device 10.

In addition, the terminal device 10 and the base station device 50 transmit and receive MAC control elements (MAC CEs) in the Medium Access Control (MAC) layer. RRC messages are transmitted as RRC Protocol Data Units (PDUs), and the logical channels to which they are mapped include the Common Control Channel (CCCH), the Dedicated Control Channel (DCCH), the Paging Control Channel (PCCH), the Broadcast Control Channel (BCCH), or the Multicast Control Channel (MCCH). MAC CEs are transmitted as MAC PDUs (or MAC subPDUs). The MAC subPDU is equal to a Service Data Unit (SDU) in the MAC layer plus, for example, an 8-bit header, and the MAC PDU includes one or more MAC subPDUs.

The physical channels and physical signals related to this embodiment will be described below. Among the physical channels related to the embodiment of the present invention, the physical broadcast channel (PBCH), the primary synchronization signal (PSS), the secondary synchronization signal (SSS), the physical random access channel (PRACH), and the physical downlink control channel (PDCCH) will be described below. In addition, in the mobile communication system according to the embodiment, at least the physical uplink control channel (PUCCH), the physical downlink shared channel (PDSCH), the physical uplink shared channel (PUSCH), the scheduling reference signal (SRS), and the demodulation reference signal (DMRS) are also present, but detailed description will be omitted.

<Physical Broadcast Channel (PBCH)>
The physical broadcast channel (PBCH) is transmitted from the base station device 50 to the terminal device 10 and is used to notify common parameters (system information) in the cells under the control of the base station device 50. The system information is further classified into a master information block (MIB) and a system information block (SIB). The system information block is further subdivided and transmitted, such as SIB1, SIB2, .... The system information includes information required for connecting to a cell, and for example, the MIB includes a system frame number and information indicating whether or not camping on a cell is possible. In addition, the SIB1 includes parameters for calculating the quality of a cell (cell selection parameters), cell-common channel information (random access control information, PUCCH control information, PUSCH control information), scheduling information of other system information, and the like. In addition, the physical broadcast channel (PBCH) is periodically transmitted as a synchronization signal block (SSB: Synchronization Signal Block (or SS/PBSH)) in a set with a synchronization signal consisting of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). By receiving the synchronization signal block (SSB), the terminal device 10 can obtain cell identifier (cell ID) information and reception timing, as well as measure the quality of the signal of the cell.

System information notified by a physical broadcast channel (PBCH) or the like is also called "system broadcast information" or "broadcast information." In addition, camping on a cell refers to a state in which the terminal device 10 completes cell selection and/or cell reselection and selects a cell for monitoring system broadcast information and paging information. The terminal device 10 establishes the above-mentioned RRC connection with the base station device 50 that forms the camped-on cell.

<Primary Synchronization Signal (PSS)>
The primary synchronization signal (PSS) is used by the terminal device 10 to synchronize with the reception symbol timing and frequency of the downlink signal of the base station device 50. The primary synchronization signal (PSS) is the signal that the terminal device 10 first attempts to detect in the procedure for detecting the cell of the base station device 50 (hereinafter also referred to as the "cell search procedure"). The primary synchronization signal (PSS) is repeatedly used as three signals, "0" to "2", based on the physical cell ID. The physical cell ID is a physical cell identifier, and 504 IDs are used in E-UTRA, and 1008 IDs are used in NR.

<Secondary Synchronization Signal (SSS)>
The secondary synchronization signal (SSS) is used by the terminal device 10 to detect the physical ID of the base station device 50. Specifically, the secondary synchronization signal (SSS) is a signal for the terminal device 10 to detect a physical cell ID in a cell search procedure. The secondary synchronization signal (SSS) is repeatedly used based on the physical cell ID, with 168 different signals from "0" to "167" in E-UTRA and 336 different signals from "0" to "335" in NR.

<Physical Random Access Channel (PRACH)>
The physical random access channel (PRACH) is used by the terminal device 10 to transmit a random access preamble to the base station device 50. The physical random access channel (PRACH) is generally used in a state in which uplink synchronization is not established between the terminal device 10 and the base station device 50, and is used for transmission timing adjustment information (timing advance) and uplink radio resource requests. Information indicating radio resources capable of transmitting the random access preamble is transmitted to the terminal using broadcast information or an RRC message.

<Physical Downlink Control Channel (PDCCH)>
The physical downlink control channel (PDCCH) is transmitted from the base station device 50 to the terminal device 10 in order to notify the terminal device 10 of downlink control information (DCI). The downlink control information includes uplink radio resource information (uplink grant (UL grant)) that the terminal device 10 can use, or downlink radio resource information (downlink grant (DL grant)). The downlink grant is information indicating the scheduling of the physical downlink shared data channel (PDSCH). The uplink grant is information indicating the scheduling of the physical uplink shared channel (PUSCH). When the physical downlink control channel (PDCCH) is transmitted as a response to a random access preamble, the physical downlink shared data channel (PDSCH) indicated by the physical downlink control channel (PDCCH) is a random access response, and includes index information of the random access preamble, transmission timing adjustment information, uplink grant, and the like.

<Hardware Configuration>
The hardware configuration of the terminal device and the base station device in the first embodiment will be described with reference to Fig. 2. Fig. 2 is a configuration diagram showing an example of the hardware configuration of the terminal device 10 and the base station device 50.

As shown in FIG. 2, the terminal device 10 and the base station device 50 each include, for example, a processor 21, a memory 22, a storage device 23, a communication device 24, an input device 25, an output device 26, an antenna 27, and a sensor 29.

The processor 21 is configured to control the operation of each part of the terminal device 10 or the base station device 50. The processor 21 is configured to include integrated circuits such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), an FPGA (Field Programmable Gate Array), and a SoC (System-on-a-chip).

The memory 22 and the storage device 23 are each configured to store programs, data, etc. The memory 22 is composed of, for example, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), and/or a RAM (Random Access Memory), etc. The storage device 23 is composed of, for example, a storage such as a HDD (Hard Disk Drive), an SSD (Solid State Drive), and/or an eMMC (embedded Multi Media Card).

The communication device 24 is configured to communicate via a wired and/or wireless network. The communication device 24 includes, for example, a network card, a communication module, etc. The communication device 24 may also include an amplifier, an RF (Radio Frequency) device that performs processing related to wireless signals, and a BB (BaseBand) device that performs baseband signal processing.

The RF device performs, for example, D/A (Digital to Analog) conversion, modulation, frequency conversion, power amplification, etc., on the digital baseband signal received from the BB device to generate a radio signal to be transmitted from the antenna 27. The RF device also performs frequency conversion, demodulation, A/D (Analog to Digital) conversion, etc., on the radio signal received from the antenna 27 to generate a digital baseband signal and transmit it to the BB device. The BB device performs a process of converting the digital baseband signal into an IP packet, and a process of converting the IP packet into a digital baseband signal.

The input device 25 is configured to allow information to be input by a user's operation. The input device 25 includes, for example, a keyboard, a touch panel, a mouse, and/or a microphone.

The output device 26 is configured to output information. The output device 26 includes, for example, a display device such as a liquid crystal display, an EL (Electro Luminescence) display, a plasma display, and/or a speaker.

Antenna 27 is configured to emit (radiate) and receive radio waves (electromagnetic waves) in one or more predetermined frequency bands. Antenna 27 may be an antenna having directionality. The gain of directional antenna 27 varies depending on the orientation of the antenna. Antenna 27 may have no directionality, i.e., be omnidirectional. Omnidirectional antenna 27 has approximately the same gain from all directions of 360 degrees in the horizontal plane, the vertical plane, or both the horizontal and vertical planes.

The antenna 27 is not limited to one. The terminal device 10 and the base station device 50 may have multiple antennas. When the terminal device 10 and the base station device 50 have multiple antennas, they may be divided into a transmitting antenna and a receiving antenna, for example. Also, when multiple antennas are divided into transmitting antennas and receiving antennas, at least one of them may include multiple antennas. Note that when the terminal device 10 and the base station device 50 have multiple transmitting/receiving antennas or transmitting antennas, the beamforming technology described below can be used.

The sensor 29 provided in the terminal device 10 includes a sensor that detects the position, orientation, and acceleration of the terminal device 10. The sensor 29 provided in the terminal device 10 includes at least one sensor of a GPS (Global Positioning System) sensor, a gyro sensor, and an acceleration sensor, for example. On the other hand, the sensor 29 provided in the base station device 50 may include a sensor that detects environmental information such as temperature, humidity, weather, or seismic intensity in the base station device 50, for example.

<Function block configuration>
(Terminal device)
The functional block configuration of the terminal device in the first embodiment will be described with reference to Fig. 3. Fig. 3 is a configuration diagram showing an example of the functional block configuration of the terminal device 10. Note that Fig. 3 is intended to show the functional blocks necessary for the description of this embodiment, and does not exclude the terminal device 10 from having functional blocks other than those shown in the figure.

The terminal device 10 has the following functional blocks: an acquisition unit 11, a receiving unit 13, a determination unit 15, a transmitting unit 17, and an access control unit 19.

The acquisition unit 11 acquires the number of MIMO layers for each of multiple CCs (component carriers). The acquisition unit 11 may acquire the number of MIMO layers for each of multiple CCs in advance from an external device, such as the core network device 90 shown in FIG. 1.

The receiver 13 receives various information from the base station device 50 shown in Figure 1. For example, the receiver 13 receives a "UECapabilityEnquiry" from the base station device 50 to inquire about the terminal capability information ("UECapabilityInformation") of the terminal device 10.

The determination unit 15 determines whether a specific number of MIMO layers satisfies a predetermined condition, for example, based on the number of MIMO layers for each of multiple CCs (component carriers) acquired by the acquisition unit 11. Details of the predetermined condition will be described later.

The transmitter 17 transmits various information to the base station device 50. For example, the transmitter 13 transmits terminal capability information of the terminal device 10 to the base station device 50 as a response to the "UECapabilityEnquiry".

For example, as shown in Figures 6 and 9 described later, the transmission unit 17 transmits to the base station device the number of MIMO layers of the frequency band (first band) of the highest Intra band 4CC CA including four (first number) component carriers (CCs) and the number of MIMO layers of the frequency band (second band) of the lowest 1CC including one (second number) CC less than four (first number). In addition, when the number of MIMO layers of the first band and the number of MIMO layers of the second band satisfy a predetermined condition, the terminal device omits transmission of the number of MIMO layers of the frequency band (third band) of the fallback CA to the base station device 50.

The access control unit 19 controls the access process (e.g., CA process) for transmitting a radio signal from the terminal device 10 to the base station device 50. The access control unit 19 controls the access process based on information related to the MIMO layer of each CC during CA set by the base station device 50.

The acquisition unit 11, the reception unit 13 and the transmission unit 17 may be realized, for example, by the communication device 24, or may be realized by the processor 21 executing a program stored in the storage device 23 in addition to the communication device 24. The determination unit 15 and the access control unit 19 may be realized by the processor 21 executing a program stored in the storage device 23. When a program is executed, the program may be stored in a storage medium. The storage medium storing the program may be a non-transitory computer readable medium. The non-transitory storage medium is not particularly limited, and may be, for example, a storage medium such as a Universal Serial Bus (USB) memory or a Compact Disc ROM (CD-ROM).

(Base station equipment)
The functional block configuration of the base station device in the first embodiment will be described with reference to Fig. 4. Fig. 4 is a configuration diagram showing an example of the functional block configuration of the base station device 50. Note that Fig. 4 is intended to show the functional blocks necessary for the explanation of this embodiment, and does not exclude the base station device 50 from having functional blocks other than those shown in the figure.

The base station device 50 has the following functional blocks: a receiver 51, a setting unit 53, a transmitter 55, and an access control unit 57.

The receiving unit 51 receives terminal capability information of the terminal device 10.

The setting unit 53 sets the MIMO layer for each CC during CA based on the terminal capability information of the terminal device 10 received by the receiving unit 51.

The transmission unit 55 transmits "UECapabilityEnquiry" to inquire about the terminal capability information of the terminal device 10. The transmission unit 55 transmits information about the MIMO layer of each CC during CA set by the setting unit 53 to the terminal device 10 as "RRCReconfiguration".

The access control unit 57 controls the access processing (e.g., CA processing) for transmitting a radio signal from the base station device 50 to the terminal device 10. The access control unit 57 controls the access processing based on information set by the setting unit 53 regarding the MIMO layer of each CC during CA set by the base station device 50.

The receiving unit 51 and the transmitting unit 55 may be realized, for example, by the communication device 24, or may be realized by the processor 21 executing a program stored in the storage device 23 in addition to the communication device 24. The setting unit 53 and the access control unit 57 may be realized by the processor 21 executing a program stored in the storage device 23. When a program is executed, the program may be stored in a storage medium. The storage medium storing the program may be a computer-readable non-transitory storage medium. The non-transitory storage medium is not particularly limited, and may be, for example, a storage medium such as a USB memory or a CD-ROM.

<MIMO Layer Setting Process>
First Embodiment
An example of the MIMO layer setting process according to the first embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a flowchart showing an example of the MIMO layer setting process according to the first embodiment of the present invention. As shown in Fig. 5, the base station device 50 transmits "UECapabilityEnquiry" to the terminal device 10 (step S1). The terminal device 10 determines whether a specific number of MIMO layers satisfies a predetermined condition based on the number of MIMO layers for each of a plurality of CCs (component carriers).

Figure 6 is a conceptual diagram showing an example of a terminal capability information transmission process when the terminal device 10 implements eight antenna paths (8RF paths) in Intra band 4CC CA in the first embodiment. The terminal capability information transmitted from the terminal device 10 to the base station device 50 includes, for example, information on the MIMO layer of each CC related to various CAs that may be executed. Here, if the number of first layers of the frequency band (first band) of the highest Intra band 4CC CA including four (first number) CCs and the number of second layers of the frequency band (second band) of the lowest 1CC including one (second number) CC that is less than four (first number) satisfy the "predetermined condition", part of the terminal capability information transmitted from the terminal device 10 to the base station device 50 is omitted.

For example, the "specified conditions" include that the first number of layers is greater than or equal to the third number of layers in the frequency band (third band) of the fallback CA, and the second number of layers is greater than or equal to the number of layers of each component carrier in the third band.

First, the case of Intra band 3CC CA as the fallback CA will be described with reference to FIG. 6. The first layer number (total number of MIMO layers) is calculated as "8" based on CC#0 (2×2), CC#1 (2×2), CC#2 (2×2) and CC#3 (2×2), and the third layer number (total number of MIMO layers) of the frequency band of Intra band 3CC CA is calculated as "8" based on CC#0 (4×4), CC#1 (2×2) and CC#2 (2×2). Therefore, the first layer number "8" is equal to or greater than the third layer number "8" of the frequency band of Intra band 3CC CA. In addition, the second layer number is calculated as "4" based on CC#0 (4×4). Regarding the number of layers of each component carrier in the third band, for CC#0 (4x4) of Intra band 3CC CA, it is "4", for CC#1 (2x2), it is "2", and for CC#2 (2x2), it is "2". Therefore, the second number of layers "4" is equal to or greater than the number of layers of each component carrier in the third band ("4" or "2"). Therefore, since the "first number of layers" and the "second number of layers" satisfy the above-mentioned predetermined condition as described above, the terminal device 10 can omit the transmission of information regarding the third number of layers of the frequency band of Intra band 3CC CA.

Next, the case of Intra band 2CC CA as fallback CA will be described with reference to FIG. 6. The first layer number (total number of MIMO layers) is calculated as "8" based on CC#0 (2×2), CC#1 (2×2), CC#2 (2×2) and CC#3 (2×2), and the third layer number (total number of MIMO layers) of the frequency band of Intra band 2CC CA is calculated as "8" based on CC#0 (4×4) and CC#1 (4×4). Therefore, the first layer number "8" is equal to or greater than the third layer number "8" of the frequency band of Intra band 2CC CA. In addition, the second layer number is calculated as "4" based on CC#0 (4×4). Regarding the number of layers of each component carrier in the third band, the number is "4" for CC#0 (4x4) of Intra band 2CC CA, and "4" for CC#1 (4x4). Therefore, the second number of layers "4" is equal to or greater than the number of layers "4" of each component carrier in the third band. Therefore, since the "first number of layers" and the "second number of layers" satisfy the above-mentioned predetermined condition as described above, the terminal device 10 can also omit the transmission of information regarding the third number of layers of the frequency band of Intra band 2CC CA.

Returning to FIG. 5, the terminal device 10 transmits terminal capability information, which does not include the third layer number of the frequency band (third band) of the fallback CA, to the base station device 50 as a response to the "UECapabilityEnquiry" (step S5). That is, as shown in FIG. 5, the terminal capability information includes only the first layer number (CC#0 (2x2), CC#1 (2x2), CC#2 (2x2) and CC#3 (2x2)) of the frequency band of the highest Intra band 4CC CA, and the second layer number (CC#0 (4x4)) of the frequency band of the lowest 1CC including a single CC.

The base station device 50 sets the MIMO layer of each CC during CA based on the terminal capability information transmitted from the terminal device 10 (step S7). As shown in FIG. 6, for example, if the base station device 50 (the setting unit 53 shown in FIG. 4) receives only the first layer number (CC #0 (2 x 2), CC #1 (2 x 2), CC #2 (2 x 2) and CC #3 (2 x 2)) of the frequency band of the highest Intra band 4 CC CA and the second layer number (CC #0 (4 x 4)) of the frequency band of the lowest 1 CC including a single CC, it determines that the terminal device 10 supports (4 x 4, 2 x 2, 2 x 2) of Intra band 3 CC CA and (4 x 4, 4 x 4) of Intra band 2 CC CA. In this regard, when the base station device 50 receives information regarding a higher CC (number of layers “4”) of Intra band CC CA from the terminal device 10, the base station device 50 can determine that the terminal device 10 naturally supports the CC (number of layers “4”) and a lower CC (number of layers “2”).

The base station device 50 transmits information regarding the MIMO layer of each CC during the configured CA to the terminal device 10 as "RRCReconfiguration" (step S9).

As described above, according to the first embodiment, the terminal device 10 transmits to the base station device the first number of layers of the frequency band (first band) of the highest Intra band 4CC CA including four (first number) component carriers (CCs) and the second number of layers of the frequency band (second band) of the lowest 1CC including one (second number) CC that is less than four (first number). When the first number of layers and the second number of layers satisfy a predetermined condition, the terminal device omits transmission to the base station device of the third number of layers of the frequency band (third band) of the fallback CA including two or three (third number) CCs that are less than four (first number) and more than one (second number). Thus, the terminal device 10 can significantly omit the terminal capability information to be transmitted to the base station device 50. Therefore, the utilization efficiency of the wireless communication resources between the terminal device 10 and the base station device 50 can be improved.

Second Embodiment
The second embodiment differs from the first embodiment in that the terminal device 10 voluntarily omits transmission of part of the terminal capability information in that the terminal device 10 omits transmission of part of the terminal capability information based on a prior notification from the base station device 50. The following will particularly describe the differences from the first embodiment.

With reference to Figure 7, an example of a MIMO layer setting process according to the second embodiment will be described. Figure 7 is a flowchart showing an example of a MIMO layer setting process during carrier aggregation in the second embodiment. Note that steps S13, S17, and S19 in Figure 7 are the same processes as steps S3, S7, and S9 in Figure 5, and therefore description thereof will be omitted.

7, the terminal device 10 receives advance notification from the base station device that transmission of at least a part of the terminal capability information (information on the number of layers for each of multiple component carriers) can be omitted (step S11). The advance notification may be included in the "UECapabilityEnquiry" and transmitted to the terminal device 10.

When the terminal device 10 receives the advance notification, the transmission of information regarding the third layer number of the frequency band of the fallback CA is omitted, and the terminal device 10 transmits terminal capability information including only information regarding the first layer number and the second layer number to the base station device 50. The terminal capability information may include information (response information) indicating that the information regarding the third layer number of the frequency band of the fallback CA has been omitted (step S15).

As described above, according to the second embodiment, the terminal device 10 omits transmission of part of the terminal capability information based on a prior notification from the base station device 50, and transmits response information corresponding to the notification to the base station device. Therefore, when the base station device 50 receives the response information, it can grasp that part of the terminal capability information transmitted from the terminal device 10 has been omitted. In other words, the base station device 50 can determine that the MIMO layer information not included in the terminal capability information is not information about a MIMO layer not supported by the terminal device 10, but information about a MIMO layer whose transmission has been omitted in the terminal device 10.

Third Embodiment
The third embodiment is different from the first embodiment, which specifies the transmission process of terminal capability information when the terminal device 10 has 8 antenna paths (8 RF paths) implemented in Intra band 4CC CA, in that the third embodiment specifies the transmission process of terminal capability information when the terminal device 10 has 12 antenna paths (12 RF paths) implemented in Intra band 4CC CA. Hereinafter, the differences from the first embodiment will be particularly described.

An example of a MIMO layer setting process according to the third embodiment will be described with reference to Figures 8 and 9. Figure 8 is a flowchart showing an example of a MIMO layer setting process during carrier aggregation in the third embodiment. Figure 9 is a conceptual diagram showing an example of a terminal capability information transmission process in the third embodiment. Note that steps S21 and S29 in Figure 9 are the same processes as steps S1 and S9 in Figure 5, and therefore description thereof will be omitted.

8 and 9, since the terminal device 10 implements 12 antenna paths (12 RF paths) in Intra band 4CC CA, the maximum number of MIMO layers is "12". In addition, the number of first layers in the frequency band (first band) of the highest Intra band 4CC CA, which includes four (first number) CCs, is "8". Therefore, in the third embodiment, it is assumed that the maximum number of MIMO layers and the number of first layers are different. In the third embodiment, too, if the "predetermined condition" is satisfied, part of the terminal capability information transmitted from the terminal device 10 to the base station device 50 is omitted (steps S23 and S25).

For example, the "specified conditions" include that the maximum number of MIMO layers is greater than or equal to the third number of layers and that the second number of layers is greater than or equal to the number of layers of each component carrier in the third band.

First, the case of Intra band 3CC CA as the fallback CA will be described with reference to FIG. 9. As described above, the maximum number of MIMO layers is "12". The third layer number (total number of MIMO layers) is calculated as "8" based on CC#0 (4×4), CC#1 (2×2) and CC#2 (2×2). Therefore, the maximum number of MIMO layers "12" is equal to or greater than the third layer number "8". In addition, the second layer number is calculated as "4" based on CC#0 (4×4). As for the number of layers of each component carrier in the third band, for CC#0 (4×4) of Intra band 3CC CA, it is "4", for CC#1 (2×2), it is "2", and for CC#2 (2×2), it is "2". Therefore, the second layer number "4" is equal to or greater than the layer number ("4" or "2") of each component carrier in the third band. Therefore, since the "maximum number of MIMO layers" and the "second layer number" satisfy the above-mentioned predetermined condition as described above, the terminal device 10 can omit the transmission of information regarding the third layer number of the frequency band of Intra band 3CC CA.

In addition, in the case of Intra band 2CC CA as the fallback CA, if certain conditions are satisfied, as in the case of Intra band 3CC CA, the terminal device 10 can omit transmitting information regarding the number of third layers in the frequency band of Intra band 2CC CA.

As shown in FIG. 8, the terminal capability information includes only the first layer number (CC#0 (2x2), CC#1 (2x2), CC#2 (2x2) and CC#3 (2x2)) of the highest Intra band 4CC CA frequency band, and the second layer number (CC#0 (4x4)) of the lowest 1CC frequency band including a single CC. The terminal capability information may further include information regarding the maximum number of MIMO layers.

The base station device 50 sets the MIMO layer for each CC during CA based on the terminal capability information transmitted from the terminal device 10 (step S27). As shown in FIG. 8 , for example, if the base station device 50 (the setting unit 53 shown in FIG. 4 ) receives only the first layer number (CC #0 (2×2), CC #1 (2×2), CC #2 (2×2), and CC #3 (2×2)) of the frequency band of the highest Intra band 4CC CA and the second layer number (CC #0 (4×4)) of the frequency band of the lowest 1 CC including a single CC, the base station device 50 determines that the terminal device 10 supports (4×4, 4×4, 4×4), (4×4, 4×4, 2×2), and (4×4, 2×2, 2×2) of Intra band 3CC CA, and (4×4, 4×4) of Intra band 2CC CA.

As described above, according to the third embodiment, even if the maximum number of layers that can be used in CA in each band is different from the first number of layers, if certain conditions are met, the terminal device 10 can omit transmitting part of the terminal capability information.

The above-described embodiments are intended to facilitate understanding of the present invention and are not to be construed as limiting the present invention. The present invention may be modified/improved without departing from the spirit thereof, and equivalents are also included in the present invention. Furthermore, the present invention can form various disclosures by appropriate combinations of multiple components disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components may be appropriately combined in different embodiments.

10 (10-1...10-m)...Terminal device, 11...Acquisition unit, 13, 51...Reception unit, 15...Determination unit, 17, 55...Transmission unit, 19, 57...Access control unit, 21...Processor, 22...Memory, 23...Storage device, 24...Communication device, 25...Input device, 26...Output device, 27...Antenna, 29...Sensor, 50 (50-1...50-n)...Base station device, 53...Setting unit, 90...Core network device, 100...Mobile communication system

Claims (6)

A terminal device in a mobile communication system compatible with carrier aggregation,
An acquisition unit for acquiring the number of layers for each of a plurality of component carriers;
a transmitter configured to transmit, to a base station device, a first number of layers of a first band including a first number of component carriers and a second number of layers of a second band including a second number of component carriers that is smaller than the first number;
the transmitting unit omits, when the first number of layers and the second number of layers satisfy a predetermined condition, transmission of a third number of layers of a third band including a third number of component carriers that is less than the first number and more than the second number to the base station device.
Terminal device. The predetermined condition is:
the first number of layers is equal to or greater than the third number of layers, and
The second number of layers is equal to or greater than the number of layers of each component carrier in the third band.
The terminal device according to claim 1 . the second band includes a single component carrier;
The terminal device according to claim 1 or 2. a receiving unit that receives, from the base station device, a notification that transmission of at least a part of the number of layers for each of the plurality of component carriers can be omitted;
When receiving the notification, the transmission unit omits transmission of the third layer number to the base station device, and transmits response information corresponding to the notification to the base station device.
The terminal device according to any one of claims 1 to 3. the transmitting unit omits transmission of the third number of layers to the base station device when a maximum number of layers available for the carrier aggregation in each band is different from the first number of layers, the maximum number of layers is equal to or greater than the third number of layers, and the second number of layers is equal to or greater than the number of layers of each component carrier in the third band;
The terminal device according to any one of claims 1 to 4. A wireless communication method used by a terminal device in a mobile communication system compatible with carrier aggregation,
obtaining a number of layers for each of a plurality of component carriers;
transmitting, to a base station device, a first number of layers of a first band including a first number of component carriers and a second number of layers of a second band including a second number of component carriers less than the first number;
the transmitting step, when the first number of layers and the second number of layers satisfy a predetermined condition, omits transmission of a third number of layers of a third band including a third number of component carriers that is less than the first number and more than the second number to the base station device.
A wireless communication method.

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